So I typed that into Google... number one result leads to a Wikipedia
story about Acetone Peroxide, aka triacetone triperoxide, peroxyacetone, TATP, and TCAP.

Interestingly, "...TATP is used in a a toy pyrotechnic device known as
a "torpedo", consisting of a twist of paper containing gravel coated
with a small quantity of TATP. These are thrown onto the ground,
producing a satisfying bang. These "torpedoes" are available legally
in states that allow firework sales such as Louisiana and Wisconsin.
They are sold illegally in the "Chinatown" districts of San Francisco
and Los Angeles (California)..." (Ed note: see update below).

It may also have been used in the 7/7 London bombings and in Richard "Shoe
Bomber" Reid's shoes, and is said to be a favorite of Hamas.

All the news organizations I saw refrained from
mentioning TATP but it's an open secret. The public should know so
they can pressure the government to seek ways to detect it.
Researchers at Technion-Israel Institute of Technology claim to have
done just that. That article also has some interesting data points on how TATP works:

"...The research team demonstrated that TATP exploded not by releasing
thermal energy, but by suddenly breaking each molecule of TATP in the
solid state into four molecules of gas. Although the gas is at room
temperature, it has the same density as the solid, and four times as
many molecules, so it has 200 times the pressure of the surrounding
air. This enormous pressure – one-a-half tons per square inch – then
pushes outward, creating an explosive force 80% greater than that of
TNT..."
Correction/Reader Comment: Privacy-Loving Reader #2 whispers:

I would profess some expertise on the subject of TATP, as I have worked extensively with it under various contracts with the federal government. All are in the past, and well behind me- before 9/11, to be precise. However, I understand a great deal about the synthesis, handling, and testing of the compound in question.

That TATP is used in "snappers" or, as you cite from Wikipedia, "torpedos," is categorically false. The compound used in these is called silver fulminate, and the Wikipedia entry for that compound is quite accurate, noting that "Silver fulminate is used in "trick noise-makers", a popular type of novelty firework."

TATP would be of little to no use in toy noisemakers as the compound is prone to subliming, i.e.: going straight from the solid form to the gaseous form. Again, the Wikipedia entry is incorrect, stating that this compound goes from the trimeric form to the dimeric form. Instead, it simply forms vapor and disappears. From the Wikibooks page: "Storing acetone peroxide is not recommended, because it quickly sublimes." In this regard, it is the same as dry ice: it simply evaporates.

1) The dry-ice property means it is quite difficult to plant such bomb into check-in lugguage. (and easy to detect, just search for low temperature spots in the luggage.
2) similarly, even preparing it in airport terminal toilet is not easy. we can use (far) infrared sensor at the gate
3) if it can be detonated so easily (friction heat/etc), there is no point banning iPod and other batteries
a) one can use the eletric wire (eg short-circuiting the shaver outlet, or lights)
b) perhaps even striking 2 pieces of stones (disguised as jewel)
4) the key to detecting TATP preparation is plane is perhaps to look for coolants?

i think such discussion and analysis would help us improve the efficiency of TSA, and also eliminate the unneccesary hassles.

Privacy-Loving Reader #2 replies:

The similarity between dry ice and TATP ends with sublimation. TATP sublimes at room temperature not because it is cold, like dry ice, but because it its intrinsic properties. Its sublimation is slow, and can be reduced; I cannot comment on specifics, but Wikibooks notes the following: "But if it must be stored, it is recommended that it is stored under water and in a container without a cap with threads, as opening it could result in an explosion from crystalized [sic] acetone peroxide."

Ultimately, this is a passing fad; as with many issues, the government has to do something, and hope the problem gets better on its own. Realistically, there are tens or hundreds of ways to disrupt air travel; historically, it has been everything from the fake bomb employed by D.B. Cooper to nitroglycerin in Philippine Airlines flight 434 to Semtex in Pan Am 103. TATP is just the latest thing to get everyone all worried, until something new comes along. Then we'll hail the new detection schemes as being brilliant and effective and worry about the next problem.

Ultimately, all solutions to terrorism issues are political, not technological, as the origins are political. It took years for the British to figure this out; finally, they sat down with the IRA and said, "What the hell do you want?" The IRA had slowly progressed from blowing up people to blowing up cars to finally calling in bombs that were going to go off at 2 AM when the streets were deserted. "If you don't mind, please keep this bomb from going off. We found out killing people makes us unpopular. Thanks!"

A combination of arrests, killings, and negotiations brought the problem to a halt- not better bomb-detectors, or silliness about removing shoes before getting on planes.

Yet another reader, Alexander Ford, adds:

There's a serious misconception in the comments you recently posted by sun-bin. He seems to believe, due to PLR#2's analogy to dry ice, that because TATP sublimates it's solid phase must be very cold, which is obviously false. It's actually similar to naphthalene, the substance used in mothballs, in that it sublimates but can be a crystalline solid at room temperature.

Jim Hill says,

So it appears the Feds were anticipating that terrorists were going to bring the raw materials for acetone peroxide (acetone, hydrogen peroxide, and a bit of hydrochloric acid {I think]) and were then going to set up a laboratory where the AP would be synthesized, precipitated from solution, collected and dried before use? what was their cover story going to be - that they were making a cup o' noodles?

There are explosive compounds that exist and are used in the liquid state - Astrolite, for example (once touted as the world most powerful non-nuclear explosive) but Astrolite needs a blasting cap to set it off - otherwise it burns like charcoal lighter. Really bad smelling charcoal lighter, yes; but it won't just go boom unless it gets a high velocity shock wave propagated through it. That's why professionals like it - it is safe to handle and predictable.

What's next? Al qaeda buying up vast quantities of tincture of iodine to make nitrogen tri-iodide? Scraping the "good stuff" off of match heads?
I didn't know the Anarchist's Cookbook was available in Arabic.

I was a high school chemistry geek back when it was legal.

]]>Time Magazine identifies the explosive that the [alleged, would-be] plane bombers were going to
use: TATP, according to UK investigators.

So I typed that into Google... number one result leads to a Wikipedia
story about Acetone Peroxide, aka triacetone triperoxide, peroxyacetone, TATP, and TCAP.

Interestingly, "...TATP is used in a a toy pyrotechnic device known as
a "torpedo", consisting of a twist of paper containing gravel coated
with a small quantity of TATP. These are thrown onto the ground,
producing a satisfying bang. These "torpedoes" are available legally
in states that allow firework sales such as Louisiana and Wisconsin.
They are sold illegally in the "Chinatown" districts of San Francisco
and Los Angeles (California)..." (Ed note: see update below).

It may also have been used in the 7/7 London bombings and in Richard "Shoe
Bomber" Reid's shoes, and is said to be a favorite of Hamas.

All the news organizations I saw refrained from
mentioning TATP but it's an open secret. The public should know so
they can pressure the government to seek ways to detect it.
Researchers at Technion-Israel Institute of Technology claim to have
done just that. That article also has some interesting data points on how TATP works:

"...The research team demonstrated that TATP exploded not by releasing
thermal energy, but by suddenly breaking each molecule of TATP in the
solid state into four molecules of gas. Although the gas is at room
temperature, it has the same density as the solid, and four times as
many molecules, so it has 200 times the pressure of the surrounding
air. This enormous pressure – one-a-half tons per square inch – then
pushes outward, creating an explosive force 80% greater than that of
TNT..."
Correction/Reader Comment: Privacy-Loving Reader #2 whispers:

I would profess some expertise on the subject of TATP, as I have worked extensively with it under various contracts with the federal government. All are in the past, and well behind me- before 9/11, to be precise. However, I understand a great deal about the synthesis, handling, and testing of the compound in question.

That TATP is used in "snappers" or, as you cite from Wikipedia, "torpedos," is categorically false. The compound used in these is called silver fulminate, and the Wikipedia entry for that compound is quite accurate, noting that "Silver fulminate is used in "trick noise-makers", a popular type of novelty firework."

TATP would be of little to no use in toy noisemakers as the compound is prone to subliming, i.e.: going straight from the solid form to the gaseous form. Again, the Wikipedia entry is incorrect, stating that this compound goes from the trimeric form to the dimeric form. Instead, it simply forms vapor and disappears. From the Wikibooks page: "Storing acetone peroxide is not recommended, because it quickly sublimes." In this regard, it is the same as dry ice: it simply evaporates.

1) The dry-ice property means it is quite difficult to plant such bomb into check-in lugguage. (and easy to detect, just search for low temperature spots in the luggage.
2) similarly, even preparing it in airport terminal toilet is not easy. we can use (far) infrared sensor at the gate
3) if it can be detonated so easily (friction heat/etc), there is no point banning iPod and other batteries
a) one can use the eletric wire (eg short-circuiting the shaver outlet, or lights)
b) perhaps even striking 2 pieces of stones (disguised as jewel)
4) the key to detecting TATP preparation is plane is perhaps to look for coolants?

i think such discussion and analysis would help us improve the efficiency of TSA, and also eliminate the unneccesary hassles.

Privacy-Loving Reader #2 replies:

The similarity between dry ice and TATP ends with sublimation. TATP sublimes at room temperature not because it is cold, like dry ice, but because it its intrinsic properties. Its sublimation is slow, and can be reduced; I cannot comment on specifics, but Wikibooks notes the following: "But if it must be stored, it is recommended that it is stored under water and in a container without a cap with threads, as opening it could result in an explosion from crystalized [sic] acetone peroxide."

Ultimately, this is a passing fad; as with many issues, the government has to do something, and hope the problem gets better on its own. Realistically, there are tens or hundreds of ways to disrupt air travel; historically, it has been everything from the fake bomb employed by D.B. Cooper to nitroglycerin in Philippine Airlines flight 434 to Semtex in Pan Am 103. TATP is just the latest thing to get everyone all worried, until something new comes along. Then we'll hail the new detection schemes as being brilliant and effective and worry about the next problem.

Ultimately, all solutions to terrorism issues are political, not technological, as the origins are political. It took years for the British to figure this out; finally, they sat down with the IRA and said, "What the hell do you want?" The IRA had slowly progressed from blowing up people to blowing up cars to finally calling in bombs that were going to go off at 2 AM when the streets were deserted. "If you don't mind, please keep this bomb from going off. We found out killing people makes us unpopular. Thanks!"

A combination of arrests, killings, and negotiations brought the problem to a halt- not better bomb-detectors, or silliness about removing shoes before getting on planes.

Yet another reader, Alexander Ford, adds:

There's a serious misconception in the comments you recently posted by sun-bin. He seems to believe, due to PLR#2's analogy to dry ice, that because TATP sublimates it's solid phase must be very cold, which is obviously false. It's actually similar to naphthalene, the substance used in mothballs, in that it sublimates but can be a crystalline solid at room temperature.

Jim Hill says,

So it appears the Feds were anticipating that terrorists were going to bring the raw materials for acetone peroxide (acetone, hydrogen peroxide, and a bit of hydrochloric acid {I think]) and were then going to set up a laboratory where the AP would be synthesized, precipitated from solution, collected and dried before use? what was their cover story going to be - that they were making a cup o' noodles?

There are explosive compounds that exist and are used in the liquid state - Astrolite, for example (once touted as the world most powerful non-nuclear explosive) but Astrolite needs a blasting cap to set it off - otherwise it burns like charcoal lighter. Really bad smelling charcoal lighter, yes; but it won't just go boom unless it gets a high velocity shock wave propagated through it. That's why professionals like it - it is safe to handle and predictable.

What's next? Al qaeda buying up vast quantities of tincture of iodine to make nitrogen tri-iodide? Scraping the "good stuff" off of match heads?
I didn't know the Anarchist's Cookbook was available in Arabic.